export interface User{
    id:number,
    username:string,
    age?:number//可选
}
export interface Phone{
    price:number,
    size:string
}
export interface propType{
    title:string
}
export interface Todo{
    text:string,
    id:number,
    done:boolean
}
export interface TodoList extends Array<Todo>{
    [index:number]:Todo
}
//记得 我们ts里面有一些interface 类型
//Array  Elment  HTMLElement   String  Boolean Number